Immunology - extra Flashcards
What is the time difference between activation of innate and adaptive immunity?
Innate is immediate. Adaptive takes 4-7 days to set in.
How does manning-binding lectin work?
Binds to mannose sugar molecules although these are quite rare in mammals.
What five substrates are involved in innate immunity?
- Interferons
- Interleukin 1 (fever symptoms)
- Mannin-binding lectin
- C-reactive protein
- Serum amyloid protein
How do c-reactive protein and serum amyloid proteins work?
Bind to the molecules found in the cell walls in bacteria and fungi.
What is clonal selection?
Where the relevant lymphocyte is activated by the foreign antigen and undergoes proliferation in order to fight off the specific pathogen.
What undergoes recombination in B and T cells?
B - immunoglobin gene segments
T - TCR gene segments
What differs in T lymphocytes in the young and the elderly?
Same number of T cells but less diversity when older - become oligoclonal.
How does the thymus change during an infection?
No apparent change
Where is Peyer’s patch found?
Lining of the gut (mainly B cells found here in the germinal centre)
What is another name for the dendritic cells found in the skin/mucosa?
Epidermal langerhaans cells
What is the function of the spleen and basic structure?
Filters the blood for antigens.
- The white pulp is directly next to the blood vessels perfused the organ, which is where the lymphocytes are found.
What is the implication of having no spleen?
Immunocompromised, especially with encapsulated pathogens. People with their spleen removed must be vaccinated against these pathogens.
How is a lymph node structured?
- Highly organised with different areas for B and T cells
- B cells aggregate towards the edge in follicles and form germinal centres in ongoing infections (this is what causes the lymph nodes to swell when you are ill)
- T cells are found slightly further towards the centre of the lymph node
How are the CD3 polypeptides helpful on T cells?
Have longer cytoplasmic tails than the two protein chains expressed by the TCR so they are important in delivering the signal to the T cell when the correct antigen is encountered.
- Have tyrosine residues that are phosphorylated upon encountering the antigen.
Where do T cells recognise antigens?
In secondary lymphoid organs.
Where are dendritic cells found?
Widely distributed but mainly found in skin and mucosa.
Where are macrophages and B cells found?
Lymphoid tissue
What is diapedesis?
Movement of a cell across the endothelial layer.
Other than epidermal langerhaans and intraepidermal lymphocytes, what other cells are helpful in detecting infection in the skin?
Keratinocytes - good at recognising damage int he skin and can secrete signalling molecules to communicate this.
How is a neutrophil distinguished?
Multi-lobed nucleus
How is a eosinophil distinguished?
Bi-lobed nucleus
How is a basophil distinguished?
Bi-lobed nucleus
What are neutrophil extracellular traps and when are they used?
When neutrophils are heavily activated they release granules proteins and nets that trap extracellular bacteria and immobilise them.
What is the structure of the constant region of an antibody?
Barrel-shaped beta pleated sheet held together by highly conserved disulphide bridges.
What is somatic hypermutation?
AID - activation induced deamination.
Causes minor point mutations so that the C in GC is changed to A so T is found on the template strand. These result in slight changes in the antibody over time.
How do the Class I and II MHC molecules differ in structure?
- MHC I only have one transmembrane tail whereas MHC II has two
- MHC I has three alpha domains and one beta domain which is a microglobulin (same in everyone)
- MHC II have two alpha domains and two beta domains
- Alpha and beta domains are held together by non-covalent bonds in both MHC molecules
Where is the HLA gene found?
Chromosome 6
Which MHC class presents longer peptides?
MHC II
What are toll-like receptors?
Class of transmembrane pattern recognition receptors (PRRs) that sense invading pathogens or endogenous damage signals. Able to initiate innate and adaptive immune responses.
- 10 found in humans
3,7,8,9 - recognise foreign nucleic acids
1,2,4,5,6,10 - recognise microbial constituents
